Best nine cylinder radial fighter

Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules

The CW-21 was an attempt to build a cheap lightweight fighter that was easily marketed to foreign customers. Air Enthusiast 16 has a great piece about the aircraft. It wasn't well engineered and had a lot of "bugs" that needed to be worked out, unfortunately, the Dutch, who were the major customer, didn't have the time and resources to address the issues.

The Japanese very easily handled the CW-21 although a few did down Zeros. I think another reason for it's dismal performance were the tactics being used at the time.
 
Climb performance numbers seem to be a bit erratic.
Initial climb may have been done at take-off rating (none of these engines had a military rating) and the take-off rating may have only good for one minute?

For the CW-21 the initial climb is listed as 4,800fpm and a time of 6 minutes to 20,000ft.
For the CW-21B the initial climb is listed as 4,500fpm and a time of 4.0 minutes to 13,120ft (4,000 meters rounded off)

Some of the weights look a little off.
CW-21 had an empty weight of 3148lbs, a useful load of 1032lbs and gross weight of 4180lbs.
It was supposed to hold 96 US gallons of fuel and 8.5 gallons of oil.
If we use the standard 200lbs for the Pilot that leaves
193lbs for guns, ammo and radio?
A single .50 cal with 200 rounds and a single .30 cal with 500 rounds are close to 170lbs.
Granted pre or early war pilots were often not fed as well as later pilots and we can find 180lb or even 160lb listed for pilots but the advertised 4 gun armament and any extra equipment (like a radio) is going to take a bite out of the climb performance.
 
It seems like some of that data was skewed a bit by CW to promote sales. I wonder if there were any test reports from Wright Patterson?

I did find this;

"The prototype first flew on 22 September 1938, carrying the civil experimental registration NX19431. Although the CW-21 was not commissioned by the U.S. military, it was test flown at Wright Field in Dayton, Ohio. The Army Air Corps immediately rejected the aircraft, with one officer commenting that it took a genius to land it."

https://www.facebook.com/
And...

2-VLG IV claimed four aerial victories during the Netherlands East Indies campaign, but the ML-KNIL was overwhelmed by the sheer number of Japanese aircraft; almost all of its fighters were soon lost in combat or destroyed on the ground.
 
Greg,

I can't really disagree with you about the CW-21's combat record. As the OP wants the
best fighter with a 9 cylinder radial engine, and if the ranking is based on combat record, the FM-2 must surely rank near the top if not at the top. The same may also be said about SR6's I-16, and GG's B-239.

Below is a table for the 4 aircraft where wing loading and power loading are calculated for each aircraft. My understanding is that wing loading gives a rough but not a definitive idea of how well each aircraft turns, while power loading gives a rough but not a definitive idea of how well each aircraft accelerates.

Plane……….loaded weight lb…….Take off HP……..wing Loading…..power loading
CW-21B……..4,500…………………1,000……………..25.8………………4.5
FM-2…………7,487…………………1.350……………..28.8………………5.5
I-16-24……….4,215………………....1,000……………..26.2……………....4.2
B-239…………5,820…………………..950……………..27.8……………....6.1

Plane………..wing area sq ft………Engine Type
CW-21B………..174…………………Wright R-1820 G-5
FM-2……………260…………………Wright R-1820-56
I-16-24………….160………………….Shvetsov M-62
B-239……………209………………...Wright R-1820 G-5

The data for the I-16 cones from Green and Swanborough's Soviet Air Force Fighters Part 2. Data for the other aircraft can be found in Wagner's American Combat Aircraft, Third Edition. I-16 weight is 'normal loaded". All other weights are "gross or gross loaded".

Based on wing and power loadings, one might conclude that the Curtis could be a handful for the other aircraft in a one on one fight. As you pointed out, its combat record is less than sterling, but perhaps there are other reasons for that beside the aircraft itself.
FWIW
Eagledad
 

Hi Shortround. Without a good supercharger, we know there is half as much air at slightly under 20,000 feet as at sea level, so there's half as much horsepower. Seems like a good excuse to climb half as fast. If it was an R-1820, I'm pretty sure it was supercharged. But, the R-1820 started out with something under 900 hp and had a GE supercharger, Later, Wright developed their own supercharger to get the power up. I think the CW-21 had a later R-1820, an R-1820-G5, which SHOULD be a tad under 1,000 hp, so I'm assuming something like 850 hp at about 20,000 feet with the supercharger.

What do you think?
 
Too high.

For some reason some of the R-1820G5 engines were rated at 950hp for take-off and some at 1000hp or different sources use different ratings for the same engine?
At any rate the R-1820G5 is listed in the Type Certificate Data Sheets number T. C. 154 and this does agree with some sources.
in low gear:
It was good for take-off at 1000hp/2200rpm/41in hg for 5 minutes.
It was good for max continuous power of 850hp/2100rpm/35.7in hg at sea level and 850hp/2100rpm/34.0in hg at 6000ft
In High gear:
Max continuous was good for 750hp/2100rpm/33.5in hg at 15,2000ft
Take-off rating was 810hp/2100rpm/38.0in hg at 7000ft for one minute.
Take off in high gear was not supposed to be done at under 7500ft

I know the last two do not agree but that is what the notes say.
Also note that take-off power in high gear is 100rpm lower than than it is in low gear. ?
Lower limits are given for 80 octane fuel instead of the 87 octane.

This is the same engine (pretty much) that the F2A-1/B239 used.

Type Certificate Data Sheets number T. C. 157 is for the R-1820G2 with single speed supercharger
Type Certificate Data Sheets number T. C. 171 is for the R-1820G3 with single speed supercharger
There are some military models listed in the 3 sheets.
Strangely the last two sheets only allow for 1 minute at the take-off rating.

None of these engines have a military rating in these sheets which, being civilian ratings, makes sense.
 
Gentlemen

Starting after page 33 in the publication, I believe there are graphs showing Horsepower, manifold pressure and RPM for the Wright 1820 G5 engine as used on the Brewster B-239.

FWIW

Eagledad
 

Attachments

  • Brewster B-239 Pilot Manual.pdf
    4.6 MB · Views: 64

Sort of a mixed bag of specs, huh?

No wonder it is hard to nail anything down for some of the less well-documented airplanes!

We are left with a speculation "what-if."
 
Last edited:
You must log in or register to reply here.

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Similar threads

A
Best WW2 Seafire vs. best A6M Zero
Replies
9
Views
1K
Shortround6
S
Best piston engined fighter of 1945?
7 8 9
Replies
168
Views
15K
PAT303
P
Best "general purpose" prop fighter also capable of best high altitude performance
2
Replies
31
Views
3K
PAT303
P
W
The scarcity of fighter to fighter FW-190A pilot combat accounts...
2 3
Replies
52
Views
3K
GrauGeist
S
Best R-4360-powered Fighter?
Replies
14
Views
2K
Admiral Beez
A
Menu
Log in
Register